1. Field of the Invention
This invention relates to a thread-wound golf ball comprising a center ball or solid center, a thread rubber layer and a cover.
2. Prior Art
Thread-wound golf balls which have been used are of the structure shown in FIG. 1 which is generally prepared by winding rubber thread around the outer surface of a center ball 1 to form a thread rubber layer 2 and forming a cover 3 thereon. The center ball 1 may be either a solid center consisting of a hard rubber ball or a liquid center having liquid introduced into a hollow rubber ball under pressure.
Prior art thread-wound golf balls using a solid center have the advantages of good temperature dependency of repulsion meaning that repulsion is scarcely changed at a low temperature as compared with golf balls having a liquid center, and low cost. But the disadvantage is inferior feel as compared with thread-wound golf balls using a liquid center. There is a desire to improve the hitting feel of thread-wound golf balls using a solid center.
Japanese Utility Model Application Kokai No. 168852/1985 discloses a solid center of a double structure for providing an improved feel. Since the solid center has a complicated structure, the manufacture of this ball involves an extra step which eliminates the low cost feature associated with the use of a solid center. In addition, since the center ball has a discontinuous hardness boundary, the ball is undesirably less durable.